Non-invasive brain stimulation is a promising alternative therapeutic means for people suffering from brain disorders. Among various direct brain stimulation modalities, ultrasound provides distinct advantages such as non-invasiveness, focusing capability, in-depth targeting, and technical maturity of ultrasound technology. However, the mechanism, therapeutic effects, and safety of ultrasound neuromodulation are yet to be determined. To uncover these fundamental aspects of ultrasound neuromodulation, development of enabling technology, such as miniature ultrasound neuromodulation devices suitable for in vivo and in vitro studies, is essential. Recently, our group has developed a miniature MEMS ultrasound transducer, Capacitive Ultrasonic Micromachined Transducer (CMUT) ring array, that enables non-invasive neuromodulation for freely-moving small animals. The design, implementation, and in vivo results of our system are described.